Recent years have witnessed an explosion of knowledge lea-ding to a molecular understanding of the mechanisms of ac-tion of calcium on excitation and contraction coupling andits role in the regulation of contractility. This bookhighlights the most recent progress as well as providing ahistorial perspective of the field. It presents a conciseand comprehensive overview of our current knowledge regar-ding calcium channels and regulatory proteins as well as in-tracellular calcium handling and the mechanisms underlyingthe activation of contractile proteins. It also describeshow these basic mechanisms have been adapted in varioustypes of muscle, especially in cardiac and smooth muscle.